In a mobile body wireless communication system, an improvement of use efficiency of a frequency as limited resources has been a problem since expanding of bandwidth in a system band has been progressed due to a rapid increase in traffic. As a technology for improving frequency use efficiency, there is Clustered Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing (DFT-S-OFDM) (refer to NPL 1). The Clustered DFT-S-OFDM is also referred to as a Dynamic Spectrum Control (DSC), and DFT-S-OFDM with a Spectrum Division Control (SDC).
In the Clustered DFT-S-OFDM where a single carrier spectrum is divided into clusters as a partial spectrum, it is possible to allocate the clusters to a frequency having high channel gain in a band. In case of such discrete band allocating, when a plurality of users perform a frequency division multiple access (FDMA), respectively, since a user is allocated to a certain band which is limited to one user, it is not necessarily the case that all of users are able to use a frequency with high gain. For this reason, in order to gain maximum channel gain even in a case in which a data transmission is performed in the plurality of users, a data transmission in which a part of spectrum is allowed to be overlapped among the plurality of users has been studied (refer to PTL 1). Even in such data transmission in which inter-user interference occurs, it is possible to detect a signal of each user using a reception device by applying a turbo equalization technology as an iterative equalization technology. Here, the turbo equalization is a technology in which a signal is detected by iteration process based on a turbo principle among a Maximum A Posteriori (MAP) detector and a decoder to exchange extrinsic information.